Recently, solar power generation systems which generate electric power using solar energy have spread even to ordinary houses. FIG. 21 is a conceptual diagram showing an ordinary house to which a solar power generation system is introduced.
In the ordinary house shown in FIG. 21, a load device 904, which is a household electrical appliance, is connected to an electric power system 903, a solar power generation apparatus 901, and a storage battery 902. The electric power system 903 here is a system for power supplied from an electric power company. Also, the solar power generation apparatus 901 is an apparatus which generates electric power using solar energy. Also, the storage battery 902 is an apparatus intended to accumulate the electric power generated by the solar power generation apparatus 901. The load device 904 is supplied with electric power from these power sources.
For example, when sufficient electric power is available from the solar power generation apparatus 901, the load device 904 is supplied with electric power from the solar power generation apparatus 901. When sufficient electric power is not available from the solar power generation apparatus 901, electric power is supplemented by the storage battery 902. Furthermore, when power supply from the solar power generation apparatus 901 and storage battery 902 is deficient, electric power is supplemented by the electric power system 903. Consequently, the load device 904 is supplied with electric power from at least one of the solar power generation apparatus 901, storage battery 902, and electric power system 903.
Examples of solar power generation systems such as described above include a solar power generation system described in Patent Literature 1.